Heretofore, a multistep fluid control valve has been proposed which is operated in a plurality of control steps depending upon various temperatures of an engine when the control valve is to be opened and closed in case, for example, the control of the ignition timing and the circulation rate of the exhaust gas back into the engine is carried out by sensing the variation in the temperature of the engine. Such a multistep fluid control valve heretofore proposed utilizes a cylindrical valve case in which a valve body in the form of a piston is slidably mounted and fluid conducting openings formed in the side wall of the valve case are opened or closed by the sliding surface of the valve body when the same is moved. Such a multistep fluid control valve is very inaccurate in the opening and closing operation while the sealing characteristics is deteriorated, because the fluid conducting openings are opened or closed by the sliding surface of the valve body.
The present invention is proposed to eliminate the above described disadvantages of the prior art multistep fluid control valve.